When designing a drive for a machine it is advisable to specify data for use in tensioning the drive. Many users of V-belt drives rely on their experience and the general rules for tensioning drives, but it has become a common practice to actually measure the tension in a drive. Numerical methods for tensioning a drive have several advantages, for example, they prevent inexperienced personnel from drastically overtensioning or undertensioning a drive, thus preventing possible bearing or belt damage. Even with experienced personnel, it helps the individual to get a feel for the tension needed in a particular drive. This is especially important with modern drives, where each V-belt is rated for higher horsepower than were previous belts. If a belt is to carry more horsepower, it must be installed proportionally tighter. Experience with older drives may lead to undertensioning of modern drives unless tension is measured at least once to help get the feel for correct tension.